A pair of spring-damper-connected inverted pendulums are introduced to model two dancers' body dynamics in physical interaction. When timing errors are included in the model, condition for poly-quadratic stability is implemented to examine the system. With two laser ranger finders installed on the robot for measuring human dancer's states, a state-feedback-based method is proposed to minimize the interaction force; because in simulation the theoretically optimal feedback gain is sensitive to measurement noise, another set of empirical gains are used and proved to be effective in experiments.